We profile the incomparable SM.
Observing 50 year old events through modern eyes can make for a faulty tool, yesterday’s visions of the future tending to appear somewhat naive to twenty-first Century sensibilities – as much a consequence of socio-economic factors, evolving customer tastes, not to mention the relentless march of time itself. Few carmakers have done more to define the modern automobile than Automobiles Citroën – especially during the post-war era – not simply in design, but also in terms of systems engineering, in particular its widespread adoption of aviation-inspired, engine-driven hydraulics.
If only Citroën could have made a car as technologically and stylistically advanced, as resolutely modern as the 1970 SM, it could only have done so during this fecund (some might say profligate) period of their history. Today, the SM still appears thrillingly futuristic, yet the future to which it spoke so promisingly seems more the subject of fond regret; one where to travel by road at high speed and in considerable comfort seemed not only possible, but within the bounds of social acceptability.
Arriving on the cusp of a new decade, 1970 was also a new frontier for the French Republic. Two years on from the bitter student demonstrations on the streets of Paris, France was looking to the future. Its post-war President had retired from public life, succeeded by a modernist who championed leading-edge technology, high-speed travel and large-scale public projects like France’s nuclear programme.
Either by happenstance or design, the SM would chime with this new frontier. As futuristic as Aérospatiale’s Concorde airliner, which in November 1970 took off from Toulouse to make its first Mach-2 test flight. Keen to be associated with such an emblematic project, President Pompidou would himself go above and beyond in Concorde prototype 001, taking in a short supersonic burst over the Bay of Biscay.
No car is created in a vacuum and despite being the culmination of some of the finest minds within Citroën’s Bureau d’Études’, it was Citroën President, Pierre Bercot, who lent the SM his wholehearted support, without which it would not have left the drawing boards. Highly intelligent, independent in thought and unswerving in action, Bercot was far from a typical automotive executive. A man of culture, he appreciated poetry and fine art, counting classical pianist, Arthur Rubenstein as a personal friend.
Under Bercot’s direction, Citroën had grown into a massive conglomerate, acquiring Panhard et Levassor, truckmakers Berliet, Maserati, and entering into the Comotor joint-venture with NSU – lending critics to suggest that monsieur le President was at least as impulsive and risk-prone as Citroën’s ill-fated founder. Bercot’s Citroën was very much at the vanguard of technology and avant-garde design, so not only did he view the SM as a necessary step, he dismissed his critic’s objections as trivialities.
To his eyes, Citroën’s purpose was to aspire not only to the best that could be possibly contrived, but to elevate the customer’s aspirations, stating, “Citroën’s character is only fully expressed in the lowest and highest market segments.” With the advent of the SM, Pierre Bercot would put this philosophy to the ultimate test.
It might be convenient from a narrative perspective to suggest that the SM came about as part of a carefully considered product plan, but that would be inaccurate. In reality, it came into being, primarily at the behest of company president, Pierre Bercot, but at a more fundamental level from another man’s determination to prove a principle. Foremost amongst Quai de Javel’s talent was André Lefèbvre, a conceptual engineer of remarkable ability, creativity and foresight.
Lefèbvre had became frustrated with some of the voices within Citroën who questioned the carmaker’s continued adherence to the traction avant formula. Determined to prove the principle, Lefèbvre set out to demonstrate that a high powered motor car was capable of being driven by its front wheels, resulting in a series of high-performance short-chassis DS models. Both cognisant and in approval of Lefèbvre’s efforts, Pierre Bercot’s sanctioned a formal research programme, lending it the title, S-vehicle, headed by Jacques Né. 1966 would prove a pivotal year, since not only did Bercot initiate Projet G (1970’s acclaimed GS), but also sanctioned development of a production S-vehicle.
The highly unusual structure and operation of Citroën’s Bureau d’Études may have created a number of technical masterpieces, but it equally resulted in a number of serious operational drawbacks, perhaps the most grievous being the lack of a cohesive singularity of purpose. This was especially true when it came to engine development. Under Bercot’s leadership, despite Citroën’s advanced integrated hydraulic systems and sophisticated chassis dynamics, engines tended to be viewed as something of an afterthought; the prevailing perception being that Citroëns, be they lowly deux chevaux or patrician DS berlines, were poorly motorisée.
The powertrain team, led by Italian, Walter Becchia had created a number of vee-formation engines with both six and eight cylinders for Jacques Né’s S-Vehicles, but the costs of production were prohibitive. Also tried were high performance versions of Maurice Sainturat’s venerable in-line four, but costs again reared their head. At this point, Bercot concluded that the answer for his nascent S-Car lay outside the Rue de Théàtre, canvassing a number of carmakers who might be interested; Citroën stipulating a lightweight alloy engine of around 2.5 litres capacity, and a V6 layout, for compactness.
One of these carmakers being Maserati; Bercot making enquires with fellow-CEO, Adolfo Orsi in 1966. Within weeks, a prototype was at the Rue de Théàtre. Highly impressed by the speed in which the Italians could work, an order for a number of prototype engines was fulfilled, and quickly fitted to Né’s S-prototypes. Bercot wasted little time, negotiating an engine supply contract before anyone else had even got off the blocks. For Maserati, Citroën’s interest was fortuitous. Facing significant costs meeting upcoming US regulations, and with an ageing product line, the necessity for collaboration was becoming glaringly apparent. For Pierre Bercot however, it went deeper than a simple engine supply arrangement.
By 1968, Bercot had purchased the Modenese atelier in its entirety, leading some to view the Citroën-Maserati takeover not so much a symbiotic coming together, but simply Monsieur le President’s Victor Kiam moment. For Bercot an equity stake would ensure Citroën had sufficient control over the supply chain – no small matter at Quai André Citroën and an entirely prudent one. But another imperative appears to have been more sentimental in nature. Far from the aloof technocrat he is generally portrayed, it seems Pierre Bercot had a genuine affection for the Modenese exotic carmaker, referring to them as “une grande maison.”
By 1967, Bercot and his Michelin masters were also engaged in advanced discussions with FIAT scion, Gianni Agnelli, and some chroniclers have suggested that the purchase of Maserati was aimed at furthering this ambition – Agnelli also known to have a soft spot for il Tridente. Cognisant however of the political ramifications surrounding a potential Franco-Italian merger, they fleshed out a collaborative deal where the Italian carmaker would assume control of Michelin’s 49% stake in Citroën.
By the close of 1968, the PARDEVI accord was complete. Bercot now President of a newly created holding company, Citroën SA, while Automobiles Citroën would administer the carmaking function, headed by new appointee, Claude Alain Sarre. With Pierre Bercot now more remote from the day to day running of the various car businesses he had worked so hard to combine, these developments would come at a crucial time for the S-vehicle programme.
Quite naturally, the SM employed Citroën’s centralised engine-driven, high-pressure hydraulics for damping, steering, braking, levelling and attitude control. This highly innovative and technically ambitious oleo-pneumatic system was developed by Paul Magès and first employed for the rear suspension of the 1954 15 h model, prior to it being rolled out in fully interconnected form in 1955’s DS 19.
Assisting Magès on Projet S was Hubert Alléra, who had designed the hydraulically actuated gearchange for the DS. Suspension-wise, the car wouldn’t depart radically from existing practice, in fact a great deal of DS thinking (and hardware) was carried over – largely for cost reasons, but also because in the opinion of Jacques Né, not only were they strong enough to cope with the car’s additional performance, they were entirely appropriate to a car of its potential.
The major departure from previous Citroën technical practice was Magès’ radical DIRAVI (DIrection a RAppel asser-VI) speed-sensitive, self-centring steering, introducing, alongside the geometrically pure centre-point steering, an unprecedented level of control. Such was its directness, an unpowered system would have rendered the car undriveable.
To alleviate this, Magès’ engineers developed a speed-sensitive variable servo, which provided maximum assist at very low speed (manoeuvring or parking) with a gradual easing of assistance as speeds rose, with zero assistance at high speeds when straight line stability was of greater importance. Coupled to this was powered self-centring, which came into effect once the handwheel was deflected from the straight ahead position, aiding high speed stability and reducing driver fatigue.
Engineers determined from their exhaustive tests of the system that the smaller movements required upon the handwheel with the DIRAVI setup combined with the ultra-quick steering ratio, saved important time during direction changes, making for quicker and safer manoeuvring.
Architecturally, given that Né was an André Lefèbvre loyalist, he would have been bound to uphold the definitive Citroën way of approaching matters. Furthermore, he was not operating with an unlimited budget, so either way there was a compelling case to be made for continuity.
Hence, the SM body structure and chassis layout closely reflected that of the existing DS, with a large pressed steel punt-shaped base unit, to which the structural elements of the SM bodyshell were welded. One notable advantage of the DS layout was that the engine’s fitment well inside the wheelbase not only aided weight distribution, but allowed for a more favourable dash to axle ratio, which a fore axle FWD layout would have made impossible.
However, this layout, with the engine mounted aft of the gearbox and final drive, was not particularly space efficient, and despite the engine being tucked snugly against the bulkhead, there entailed a long frontal overhang – fortunately another Citroën tradition. A further advantage of this layout was a low polar moment of inertia, which aided stability and balance. All of these factors would entail that the SM was a larger car than strictly necessary, more so even than the more commodious DS saloon.
The SM also brought a new sophistication to something as prosaic as lighting, hydraulics being employed to provide automatic levelling for the six quartz halogen Cibie headlamps; the inner pair also turning in harmony with steering inputs. Following DS practice, the SM employed a pressure sensitive brake button, which operated the four wheel discs, the front brakes mounted inboard, alongside the final drive unit.
So, irrespective of how Citroën’s Bureau d’Études was acting, the technicalities of the SM would be Quai de Javel distillate in its purest form.
 Tellingly, Citroën UK’s Oct 13 1970 press release for the launch of the SM contained the following: “It can be said that the SM represents as marked a contrast between not only the DS and other cars of the Grand Touring class, but also as between the Caravelle and the Concorde.” (The Caravelle being Sud Aviation’s pioneering jet airliner from the 1950s). [Source: sm-uk.com]
 Victor Kiam was a US businessman who became a household name in the 1970s fronting a long-running TV ad campaign for Remington shavers, which contained the immortal line; “I liked it so much, I bought the company”.
 The DIRAVI steering fitted to the SM employed a ratio of 9:4:1 with a mere two turns lock to lock. Magès and Né also envisaged a mechanically actuated active suspension system, which by 1975 was running in experimental prototypes, incorporating hydraulic control of roll and pitch. However, this hydro-mechanical system was deemed too complex and expensive to productionise, and was put on the shelf until such time as suitable electronic control units became available. The Hydractive system made its debut in the 1989 XM, reaching its series production apogee with the 1997 Xantia Activa model. [Source: Jan Norbye]
Sources and references:
Robert Opron L’Automobile et L’Art: Peter I Pijlman
Citroën SM : Jan P. Norbye
Citroën SM : Brian Long
Sa Majesté – Citroën SM : Peter I Pijlman/ Brian Cass
Citroën SM – Accidental Death of an Icon : Stuart Ager
André Citroen – Engineer, Explorer, Entrepreneur – John Reynolds
Maserati- The Citroën Years 1968-1975 : Marc Sonnery